ESS Energy Storage Systems

ESS / 01.

What is an ESS?

Energy Storage System is as the name suggests a device used for storing electric energy when needed and releasing it when required. The energy is then usually stored in an electrochemical form. These systems have a distinctive feature of including an accessible connection (+ and - terminals) which is capable of generating and / or storing a continuous electrical power directly (without transformation).

MTA is in capacity to test a wide range of ESS, as followed:
  • Batteries of all kind of technologies (alkaline, Li//SOCl2, Li//SO2, Li//MnO2…) [non rechargeable]
  • Lead-acid accumulators
  • NiCd accumulators
  • NiMH accumulators
  • Lithium-ion accumulators
  • Supercapacitors

A “Battery pack” consists of a multiple assembly of several accumulators (or batteries) linked in series and / or in parallel, with or without a battery management system (BMS).



ESS / 02.

Testing an ESS

During the development phase of an ESS, MTA can help you to optimize the production process with our tests facilities by addressing some critical issues:
  • Safety
  • Quality
  • Performance
  • Price
  • Lifetime

These are important points to be consistently verified throughout the ESS development to meet application requirements. Accordingly, our SSE testing solutions allow our customers to:
  • Benchmark different battery manufacturers and select one relevant cell for its performance.
  • Characterize their ESS in order to provide baseline information and precisely define their performances.
  • Obtain the electrical and thermal characteristics of their ESS to enhance their modeling capabilities.
  • Achieve endurance or aging behavior and accelerate aging protocols on ESS in order to know, model and optimize the life prediction of their product.
  • Play complex scenarios for developing the suitable BMS of their battery (transitions, security, status indicators ...)


ESS / 03.

Testing example

From the beginning of the project, a manufacturer has solicited our active participation in the project to create a battery for air transport industry. We then propose a first phase of selection of Li-ion cell to determine the one with high energy capacity and the highest power release. The procedure is as follows:

« Which one of these 18650-cell choose ? »



ESS / 04.

Result and analysis example

The work completed by MTA operators and engineers makes it possible to process the raw results obtained and to draw the following graph:

Based on customer’s need, MTA will recommend reference 1 for its excellent energy density but above all reference 2 that is the best Energy / Power tradeoff.



ESS / 05.

Our services

We provide engineering support to meet our customers specific needs including tests results analysis (see section Services and Procedures). Accordingly, we take an overall approach to supporting our customers and our ESS testing services cover a broad range of industry needs.

  • Testing from 1V-simple cell to a 600V-full battery pack.
  • Testing from basic (capacitance or resistance metrology) to complex battery systems (packs with BMS, SIL / HIL, communication interfaces ...).
  • Advanced thermal assessment, either on cells or modules, through our expertise and our equipment (many instrumentations, thermal camera, water or air thermal conditioning...).
  • Long term testing for several months without interruption, 24 hours a day.
  • Battery software (BMS) development testing (SOC indicators, SOH, transitions, modes of communication ...)
  • Characterization or mapping tests of detailed ESS over wide parameter ranges (-60°C to +70°C, from +/-1mA to +/-1000A, from 1mV to 600V)
  • Product qualification testing, according to many standards (ISO, ANSI, IEC, DO ...), along with full result report.

In any case, MTA conducts a safety study of test setup and then runs different test scenarios before offering the one that serves the client’s need.



ESS / 06.

Testing equipment

Our test equipment for ESS includes the following:

Test benches used to charge and discharge the ESS:

  • 12 test channels 0-5V, max. 1kW
  • 5 test channels 0-60V, max. 32kW
  • 5 test channels 0-600V, max. 160kW

Temperature chambers allowing thermal conditioning of the ESS environment:

  • 2 chambers 500L +15°C ↔ +70°C (calendar tests)
  • 5 chambers 150L 0°C ↔ +70°C
  • 4 chambers 600L ou 1000L -40°C ↔ +180°C
  • 4 chambers 4m3 à 11m3 -40°C ↔ +70°C

Environmental chambers equipped with air and water-cooling system for complex thermal conditioning scenarios:

  • 1 air cooling -80°C ↔ +180°C, 0 à 500m3/h
  • 1 water cooling -20°C ↔ +80°C, 0 à 2200L/h

We provide a systemic approach when it comes to perform a test by enhancing safety shielding in order to ensure operators and equipment safety:

  • Preventive safety: an anhydrous nitrogen generator, which makes it possible to work under an anhydrous atmosphere (for unvarnished electronic boards for example) and depleted in oxygen.
  • Active safety: systematic monitoring of the current, voltage and temperatures during the SSE testing
  • Curative safety: automatic gas extinguishing devices of the SSE in the event of fire detection.

Additionally, MTA can offer small equipment required for personnel and equipment protection against failure risks (insulating gloves (1000V), insulated tools, arc flash visor ...) to ensure proper handling of the ESS.

Example of curative Li-ion safety (bottle and central safety )

Additional small equipment:
MTA has acquired the equipment needed over the years in order to carry out specific or complex testing of these "system" and thus meet customers’ requirements. Here is a non-exhaustive list of materials that can be provided for ESS testing:

  • Isolation controller
  • Precision scales
  • Precision Multi-meters [100nV-1000Vdc range]
  • 1kHz AC Micro-ohmmeter for batteries [0,1µOhm-3MOhm range]
  • Power supplies
  • Electronic charges
  • Thermal video camera
  • Acquisition temperature control boxes
  • Oscilloscope
  • Portable acquisition centers

Communication protocols:
MTA has several tools (hardware & software) and skills to communicate with testing systems as well as batteries BMS. This includes CAN, Ethernet, RS232 protocols…

Calibration verification:
All measuring equipment is calibrated, internally or externally, according to strict procedures. Calibration reports are made available when requested to all our customers.